A fracture in the epiphyseal portion of a long bone may be treated with a femoral implant such as a femoral neck screw. These femoral neck screws may be coupled to a bone plate or an intramedullary nail such that the neck screws are axially displaceable relative to the bone plate or intramedullary nail to allow a dynamization in the direction of the axis of the femoral neck screw and provide an angular stability between the femoral neck screw and the bone plate or intramedullary nail.
In some cases where the fracture has not been properly reduced, however, implantation of the femoral neck screw may result in only a limited contact area between the fractured portions of the bone. Dynamization via the femoral neck screw often does not compensate for inadequate or improper fracture reduction resulting from, for example, misalignment of the two fragments. Insufficient fracture contact area can delay fracture healing which in turn can lead to cyclic overload of the screw anchorage in the femoral head. This cyclic overload may lead to implant loosening and/or implant cut out. Insufficient fracture reduction often occurs in the sagittal plane, as visualization of the fracture site in this plane is very difficult during surgical interventions. Rotation of the head fragment may increase the risk of implant cut out due to incorrect positioning of the screw.